The Chinese ASAT, a ballistic missile tipped with a destructive device, was launched on January 11th, 2007. It destroyed an old weather satellite - the Fengyun-1C spacecraft. As of today, the US military Space Surveillance Network has cataloged or is tracking more than 900 bits of debris from the explosion that are at least ten centimeters in diameter.

However, the total number of objects from this single incident reaches into the tens of thousands. NASA estimates that the number of debris fragments larger than one centimeter exceeds 35,000.

"Any of these debris has the potential for seriously disrupting or terminating the mission of operational spacecraft in low Earth orbit. This satellite breakup represents the most prolific and serious fragmentation in the course of 50 years of space operations,” said NASA’s Nicholas Johnson, Chief Scientist for Orbital Debris at the space agency’s Johnson Space Center in Houston, Texas.
(Space.com: Chinese ASAT Test)

The cloud extends from less than 125 miles to more than 2,292 miles; this range encompasses all of low Earth orbit. Chief Scientist Johnson states that "“This satellite breakup represents the most prolific and serious fragmentation in the course of 50 years of space operations."

According experts quoted in the New York Times today, the Chinese ASAT test brought closer the danger of chain reaction, or cascade, of collision events in which fragments collide with each other, creating even more objects. This would precipitate what has been called the Kessler Syndrome, after Donald J. Kessler, a former head of the orbital debris program at NASA, in which launches from Earth would become impossibly dangerous owing to the risk of collision.

Mr. Kessler frankly calls the syndrome an exaggeration. But there is no doubt that, with a single test, the Chinese government has made near space a more dangerous place for everyone.

Science fiction authors have long been concerned about debris in space. Arthur C. Clarke even proposed a solution: Operation Cleanup.

For two hundred years, satellites of all shapes and sizes, from loose nuts and bolts to entire space villages, had been accumulating in Earth orbit... Three-quarters of this material was abandoned junk, much of it long forgotten. Now it had to be located, and somehow disposed of.

Fortunately, the old orbital forts were superbly equipped for this task.
(Read more about Operation Cleanup)

Until orbital forts become available, you might want to read up on these practical solutions to the problem of space debris:

And what about "space lanes?" This is an old science fiction term referring to the idea that there were settled routes through space, similar to the sea lanes long established by mariners. One early science fiction writer to mention space lanes was Carl Jacobi, in his story Cosmic Teletype, published in Thrilling Wonder Stories in 1938.

Update 09-Feb-2007 I've located the quote from the Jacobi story; read more about space-lanes from the October, 1938 issue of Thrilling Wonder Stories. (End update.)